MOFs-derived ZnCo-Fe core-shell nanocages with remarkable oxygen evolution reaction performance

Various renewable energy systems, such as water splitting cells and metal-air batteries, are on basis of oxygen evolution reaction (OER). Replacement of common noble-metal platinum catalysts with highly efficient, cheap and operationally stable electrocatalysts opens huge potential applications for OER, thus leading increasing efforts to develop alternative efficient OER catalysts via low-cost fabrication processes. Herein, we report a facile self-templated method to synthesize Zn/Co-Fe core-shell nanocages, derived by metal-organic frameworks (MOFs), as an efficient catalyst for OER. The unique structure of Zn/Co-Fe core-shell nanocages offers a large active surface area with abundant active sites and efficient charge transfer capability, as the hollow structure facilitates the active direct contact of materials with electrolytes. We introduce this kind of catalysts at different ratios of Fe, which has a significant effect on the electrocatalystic performance of OER. In a word, the introduction of Fe not only makes the change of the composition, it also changes the morphology to expose plenty active sites for OER. Owing to the synergistic effect between element composition and the abundant actives sites, the optimized Zn/Co-Fe-20 sample presents a superior electrocatalystic performance of OER with a very low overpotential (η = 176 mV at 10 mA cm-2), also with a small Tafel slop of 69.3 mV dec-1. This strategy developed here can be easily extended to synthesize other MOFs derived polymetallic oxide-based hybrid electrodes for OER, as a practical route for the design of cheap, and efficient electrocatalysts.